Salivary glands from 3rd instar larvae of Drosophila melanogaster were dissected, fixed with formalin and stained with uranyl acetate, embedded in epoxy resin, and 0.25 micrometer sections prepared (see Ris H, 1981 Stereoscopic Electron Microscopy of Chromosomes, Meth Cell Biol 22:77-96). Grids were observed using the Madison High Voltage Electron Microscope at 1 MeV. Image shows a series of bands and interbands in a polytene chromosome. This image was taken with a tilt angle of 40 degrees. The accompanying grouped image, taken at 55 degrees forms a stereo pair, providing an oblique 3D view of the chromosome.